We have used density-functional-theory (DFT) methods together with a structure searching algorithm to make an experimentally constrained prediction of the structure of ammonia dihydrate II (ADH-II). The DFT structure is in good agreement with neutron diffraction data and verifies the prediction. The structure consists of the same basic structural elements as ADH-I, with a modest alteration to the packing, but a considerable reduction in volume. The phase diagram of the known ADH and ammonia monohydrate + water-ice structures is calculated with the Perdew-Burke-Ernzerhof density functional, and the effects of a semi-empirical dispersion corrected functional are investigated. The results of our DFT calculations of the finite-pressure elastic constants of ADH-II are compared with the available experimental data for the elastic strain coefficients.
REFERENCES
1.
2.
3.
J. S.
Lewis
and R. G.
Prinn
, Astrophys. J.
238
, 357
(1980
).4.
R. G.
Prinn
and B.
Fegley
Jr., Astrophys. J.
249
, 308
(1981
).5.
F.
Sohl
, M.
Choukroun
, J.
Kargel
, J.
Kimura
, R.
Pappalardo
, S.
Vance
, and M.
Zolotov
, Space Sci. Rev.
153
, 485
(2010
).6.
7.
A. D.
Fortes
and M.
Choukroun
, Space Sci. Rev.
153
, 185
(2010
).8.
D. L.
Hogenboom
, J. S.
Kargel
, T. C.
Holden
, and M.
Buyyounouski
, Lunar Planet. Sci.
26
, 613
(1995
).9.
D.
Hogenboom
, J.
Kargel
, G.
Consolmagno
, T.
Holden
, L.
Lee
, and M.
Buyyounouski
, Icarus
128
, 171
(1997
).10.
R. J.
Nelmes
and J. S.
Loveday
, ISIS Experimental Report RB9411, 1998
.11.
R. J.
Nelmes
, J. S.
Loveday
, and M.
Guthrie
, ISIS Experimental Report RB9859, 1998
.12.
A. D.
Fortes
, J. P.
Brodholt
, I. G.
Wood
, L.
Vočadlo
, and H. D. B.
Jenkins
, J. Chem. Phys.
115
, 7006
(2001
).13.
A.
Fortes
, I.
Wood
, J.
Brodholt
, and L.
Vočadlo
, Icarus
162
, 59
(2003
).14.
A.
Fortes
, J.
Brodholt
, I.
Wood
, and L.
Vočadlo
, J. Chem. Phys.
119
, 10806
(2003
).15.
A. D.
Fortes
, I. G.
Wood
, M.
Alfredsson
, L.
Vočadlo
, K. S.
Knight
, W. G.
Marshall
, M. G.
Tucker
, and F.
Fernandez-Alonso
, High Press. Res.
27
, 201
(2007
).16.
A. D.
Fortes
, I. G.
Wood
, L.
Vočadlo
, K. S.
Knight
, W. G.
Marshall
, M. G.
Tucker
, and F.
Fernandez-Alonso
, J. Appl. Cryst.
42
, 846
(2009
).17.
A. D.
Fortes
, E.
Suard
, M. H.
Lemée-Cailleau
, C. J.
Pickard
, and R. J.
Needs
, J. Am. Chem. Soc.
131
, 13508
(2009
).18.
A. D.
Fortes
, E.
Suard
, M. H.
Lemée-Cailleau
, C. J.
Pickard
, and R. J.
Needs
, J. Chem. Phys.
131
, 154503
(2009
).19.
C. J.
Pickard
and R. J.
Needs
, Phys. Rev. Lett.
97
, 045504
(2006
).20.
C. J.
Pickard
and R. J.
Needs
, J. Phys.: Condens. Matter
23
, 053201
(2011
).21.
C. J.
Pickard
and R. J.
Needs
, Nat. Phys.
3
, 473
(2007
).22.
C. J.
Pickard
and R. J.
Needs
, Phys. Rev. Lett.
102
, 125702
(2009
).23.
C. J.
Pickard
and R. J.
Needs
, J. Chem. Phys.
127
, 244503
(2007
).24.
C. J.
Pickard
and R. J.
Needs
, Nat. Mater.
7
, 775
(2008
).25.
J.
Bernal
and R.
Fowler
, J. Chem. Phys.
1
, 515
(1933
).26.
G. I. G.
Griffiths
, A. D.
Fortes
, A. J.
Misquitta
, C. J.
Pickard
, and R. J.
Needs
, e-print arXiv:1112.2636.27.
M. I.
Aroyo
, J. M.
Perez-Mato
, C.
Capillas
, E.
Kroumova
, S.
Ivantchev
, G.
Madariaga
, A.
Kirov
, and H.
Wondratschek
, Z. Kristallogr.
221
, 15
(2006
).28.
S. J.
Clark
, M. D.
Segall
, C. J.
Pickard
, P. J.
Hasnip
, M. I. J.
Probert
, K.
Refson
, and M. C.
Payne
, Z. Kristallogr.
220
, 567
(2005
).29.
J. P.
Perdew
, K.
Burke
, and M.
Ernzerhof
, Phys. Rev. Lett.
77
, 3865
(1996
).30.
D.
Vanderbilt
, Phys. Rev. B
41
, 7892
(1990
).31.
H. J.
Monkhorst
and J. D.
Pack
, Phys. Rev. B
13
, 5188
(1976
).32.
33.
A. C.
Larson
and R. B.
Von Dreele
, “GSAS: general structure analysis system
”, Report LAUR 86-748, Los Alamos National Laboratory, 2000
.34.
B. H.
Toby
, J. Appl. Crystallogr.
34
, 210
(2001
).35.
T.
Dunitz
, X-ray Analysis and the Structure of Organic Molecules
(Cornell University Press
, 1979
).36.
G. C.
Feast
, J.
Haestier
, L. W.
Page
, J.
Robertson
, A. L.
Thompson
, and D. J.
Watkin
, Acta Crystallogr., Sect. C: Cryst. Struct. Commun.
65
, 635
(2009
).37.
38.
M. B. J.
Boisen
and G.
Gibbs
, Rev. Mineral.
15
, 72
(1990
).39.
R. M.
Hazen
, R. T.
Downs
, and C. T.
Prewitt
, Rev. Mineral. Geochem.
41
, 1
(2000
).40.
See supplementary material at http://dx.doi.org/10.1063/1.4707930 for fitting statistics of the ab initio structure against the experimental data, the relationship between the P21/n and P21/c space groups, and sections through the elastic strain tensor representation surface.
© 2012 American Institute of Physics.
2012
American Institute of Physics
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